Thickness, subglacial relief and volume of Svalbard glaciers based on radio echo‐sounding data

Macheret, Yu. Ya.; Zhuravlev, A. B.; Bobrova, L. I.

doi:10.1080/10889378509377254

Cited by 7 publications

(6 citation statements)

References 7 publications

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“…Extensive airborne radar soundings of ice thicknesses and subglacial topography have also been undertaken of the Greenland Ice Sheet (e.g., Gudmandsen, 1969;Wright et al, 1989;Hodge et al, 1990;Hempel and Thyssen, 1993;Gudmandsen et al, 1994), the Canadian high arctic (e.g., Evans and Robin, 1966;O'Neil and Jones, 1975;Narod and Clarke, 1980;1983;Clarke et al, 1987;Narod et al, 1988), Svalbard and the Russian high arctic (e.g., Drewry et al, 1980a;Macheret, 1981;Macheret et al, 1985;Dowdeswell et al, 1984;Hagen and Saetrang, 1991), and Iceland (e.g., Björnsson, 1982;1986a;1986b;Björnsson et al, 1977;1995a;1995c).…”

Section: Determination Of the Thickness Of Ice Massesmentioning

confidence: 99%

“…These problems of scattering and poor depth penetration (e.g., 150-250 m -Macheret, 1981;Macheret and Zhuravlev, 1982) were also exacerbated Subsequent lower-frequency (60 MHz) soundings (e.g., Drewry et al, 1980a;Dowdeswell et al, 1984; resulted in unambiguous bed echoes being recorded (within 10% of independent, gravity-derived depth readings) from ice depths of up to 530 m. Dowdeswell et al (1984) also reinterpreted over 60% of earlier 'bed echoes' as IRHs. As a result of this work, Macheret et al (1985) produced an inventory of the thickness and volume of 87 ice masses in the region. However, difficulties in recording bed echoes were still encountered in 50% of the later, 60 MHz studies (Dowdeswell et al, 1986).…”

Section: Basal Conditions Of Ice Massesmentioning

confidence: 99%

“…A 'special case' IRH appears repeatedly (over 50% of glaciers) in the Svalbard inventory at a spatially constant depth of between 100 and 200 m (Macheret et al, 1985;Bamber, 1987). A similar feature has also been identified at polythermal glaciers elsewhere (e.g., Storglaciären, Sweden - Holmlund and Eriksson, 1989;Holmlund et al, 1996).…”

Section: Basal Conditions Of Ice Massesmentioning

confidence: 99%

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A review of the use of radio-echo sounding in glaciology

Plewes

Hubbard

2001

Progress in Physical Geography: Earth and Environment

119

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Radio-echo sounding (RES), or radar, is an established geophysical technique that has been, and continues to be, applied to investigate a variety of ice-mass properties. This review presents the physical theory and principles of radio-glaciology, and describes the various types of radar equipment commonly used, including modern, ground-penetrating radar (GPR) systems. The range of glaciological applications these systems have been used to investigate is summarized, along with promising avenues of current and future research.

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Section: Determination Of the Thickness Of Ice Massesmentioning

confidence: 99%

Section: Basal Conditions Of Ice Massesmentioning

confidence: 99%

Section: Basal Conditions Of Ice Massesmentioning

confidence: 99%

See 1 more Smart Citation

A review of the use of radio-echo sounding in glaciology

Plewes

Hubbard

2001

Progress in Physical Geography: Earth and Environment

119

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“…However, radar surveys carried out later could not conclusively support this hypothesis. Soviet scientists used survey data from the 1970s to conclude that the bed in the area of the ice divide lies far below sea level (Macheret et al ., ), indicating a connection between the Barents and the Greenland seas (Macheret and Zhuravlev, ). Later surveys, on the other hand, demonstrated the existence of subglacial zones below sea level only in part of this area, raising doubts on the potential continuous link between Hornsund and Hambergbukta (Dowdeswell et al ., ; Pälli et al ., ).…”

Section: Introductionmentioning

confidence: 99%

Coast formation in an Arctic area due to glacier surge and retreat: The Hornbreen–Hambergbreen case from Spistbergen

Grabiec

Ignatiuk

Jania

et al. 2017

Earth Surf Processes Landf

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Glacierised coasts undergo faster geomorphic processes than unglaciated ones. We have studied changes of the coastal area in southern Svalbard with the glacier bridge between Torell Land and Sørkapp Land since the beginning of the 20th century. The existence of a continuous subglacial depression beneath the Hornbreen–Hambergbreen glacier system has been debated since the 1960s, with inconclusive results. In this study we assess both the subglacial topography and the bathymetry of Hornsund Fjord and Hambergbukta bay. This included ~40 km of radar surveys over the glacial system and sea depth sounding. The extent of the glaciers from maps and satellite images together with digital terrain models and surface elevation data based on GPS profiling were used to analyse geometry changes of the glacier surfaces. The results confirm the existence of a continuous subglacial depression below sea level (c. 40 m deep) between Hornsund and the Barents Sea. The Hornbreen‐Hambergbreen system has changed in shape over the past century, reflecting its dynamic origin and activity, also exemplified by the sequential surges identified since 1899. There was a pre‐surge build‐up event of Flatbreen causing a surge and subsequent lowering of the Hornbreen‐Hambergbreen frontal parts by the 1960s. After, the entire surface lowered, albeit with a delay in the Hornbreen terminal zone. Since the year 2000, Hornbreen terminus has retreated at an average rate of 106 m a−1; ~50% faster than that of Hambergbreen. If the retreat continues at the 2000–2015 average rate, the ice bridge between Hornsund and Hambergbukta will be broken sometime between 2055 and 2065 and the Hornsund strait will separate Sørkapp Land from the Spitsbergen island. The processes and events described in this study, particularly the effects of the glacier surge, may provide a model for changes likely to occur in other coastal glaciated regions experiencing rapid change. Copyright © 2017 John Wiley & Sons, Ltd.

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“…Among the elastic effects, we considered here the effects of sea‐level (SL) changes and present‐day ice melting (PDIM). Radio echo‐sounding data indicate that the mean thickness averaged over all major glaciers of Svalbard is close to 200 m (Macheret et al 1985). Our preliminary computation using a simple glacier model, which uniformly covers Svalbard with a 200‐m‐thickness layer, suggests that the PDIM effect is about 2.3 mm yr −1 for the uplift of the ground and −0.4 μGal yr −1 for the gravity change when the glacier is melting at a rate of about 50 cm yr −1 .…”

Section: Introductionmentioning

confidence: 99%

A geophysical interpretation of the secular displacement and gravity rates observed at Ny-Ålesund, Svalbard in the Arctic-effects of post-glacial rebound and present-day ice melting

Sasajima

Okuno

Hinderer

et al. 2006

Geophysical Journal International

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S U M M A R YWe have analysed the Ny-Ålesund very long baseline interferometry (VLBI) data over the period 1994 August to 2004 May, and we obtain secular displacement rates relative to a NNR-NUVEL-1A reference frame of 0.2 ± 0.5 mm yr −1 , −1.7 ± 0.5 mm yr −1 and 4.8 ± 1.1 mm yr −1 for the north, east and vertical directions, respectively. The corresponding global positioning system (GPS) station displacement rates relative to the same reference frame for the north, east, and vertical directions are 0.2 ± 0.6 mm yr −1 , −2.3 ± 0.6 mm yr −1 , and 6.4 ± 1.5 mm yr −1 at NYA1 and -−0.1 ± 0.5 mm yr −1 , −1.6 ± 0.5 mm yr −1 , and 6.9 ± 0.9 mm yr −1 at NALL, where these GPS rates were derived from the ITRF2000 velocity solution of Heflin. From the comparison at 25 globally distributed collocated sites, we found that the difference in uplift rate between VLBI and GPS at Ny-Ålesund is mainly due to a GPS reference frame scale rate error corresponding to 1.6 mm yr −1 in the GPS vertical rates. The uplift rate was estimated to be 5.2 ± 0.3 mm yr −1 from the analysis of the tide gauge data at Ny-Ålesund. Hence the uplift rates obtained from three different kinds of data are very consistent each other. The absolute gravity (AG) measurements at Ny-Ålesund, which were carried out four times (period: 1998-2002) by three different FG5 absolute gravimeters, lead to a decreasing secular rate of −2.5 ± 0.9 μGal yr −1 (1 μGal = 10 −8 m s −2 ). In this analysis, the actual data obtained from a superconducting gravimeter at Ny-Ålesund were used in the corrections for the gravity tide (including the ocean tide effect) and for the air pressure effect. We have estimated three geophysical contributions to examine the observed rates: (1) the effect of the sea-level (SL) change on a timescale of a few decades, (2) the effect of the present-day ice melting (PDIM) in Svalbard and (3) the sensitivity of the computed post-glacial rebound (PGR) effects to different choices of the models of past ice history and Earth's viscosity parameters. Our analysis indicates that the effect of SL change can be neglected as the main source of the discrepancy. On the other hand, the effect of PDIM cannot be ignored in explaining the mutual relation between the observed horizontal and vertical rates and the predicted ones. A large melting rate of the order of −75 cm yr 11 (i.e. roughly 1.6 times larger than the mean rate derived from glaciology over Svalbard) would explain the observed uplift but only half of the gravity changes. Our comparison results clearly point out the importance of both the estimation accuracy of the elastic deformations and better observation accuracy to constrain the size of PGR effects in the northwestern Svalbard more tightly.

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Thickness, subglacial relief and volume of Svalbard glaciers based on radio echo‐sounding data

Cited by 7 publications

References 7 publications

A review of the use of radio-echo sounding in glaciology

A review of the use of radio-echo sounding in glaciology

Coast formation in an Arctic area due to glacier surge and retreat: The Hornbreen–Hambergbreen case from Spistbergen

A geophysical interpretation of the secular displacement and gravity rates observed at Ny-Ålesund, Svalbard in the Arctic-effects of post-glacial rebound and present-day ice melting

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